1. Field of the Invention
The invention relates generally to a method for simultaneous extraction of essential oils and antioxidants from organic material, more particularly organic material from the Lamiaceae (or Labiatae) family, including rosemary (Rosemarinus officinalis) and, more specifically, to a method of simultaneous extraction of essential oils and antioxidants from species of the family Labiatae, in particular, rosemary, using solvent blends and which yields a liquid, oily extract containing antioxidants and a liquid extract containing essential oils. The extract containing antioxidants is readily mixed with an edible oil for addition to animal feeds and human food. The essential oils are pharmaceutical grade.
2. Background of the Prior Art
Worldwide demand for natural antioxidants has been rising due to safety concerns about synthetic food and feed additives and the public perception that natural food and feed supplements provide certain health benefits. The most important natural antioxidants being exploited commercially today are tocopherols. Tocopherols have a potent ability to inhibit lipid peroxidation in vivo by trapping peroxy-radicals (Burton, G. W., and K. U. Ingold (1989), in Vitamin E: Biochemistry and Health Implications, edited by A. T. Diplock, L. J. Machlin, L. Packer and W. A. Pryor, The New York Academy of Sciences, New York, pp. 7-22). Various herbal extracts for use as natural antioxidants are being explored. Possibilities include the extraction of rosemary or other botanical sources. Such new antioxidants may play a role in combating carcinogenesis as well as the aging process, and may be applicable in the nutraceutical industry.
Among the various natural extracts available in the market are rosemary extracts, which are reported to be highly effective in retarding lipid oxidation and protecting living cells from the damaging oxidative stress (Chen, Q., H. Shi and C-T Ho (1992), “Effects of rosemary extracts and major constituents on lipid oxidation and soybean lipoxygenase activity”, J Am Oil Chem Soc 69: 999-1002; Wong, J. W., K. Hashimoto and T. Shibamoto (1995), “Antioxidant activities of rosemary and sage extracts and vitamin E in a model meat system”, J Agric Food Chem 43: 2707-2712). These extracts are described as being superior to vitamin E, a well-known natural antioxidant and food supplement, in many food model systems (Lolinge, J. (1983), Natural antioxidants in Allen, J. C. and R. J. Hamilton eds, Rancidity in Foods, Elsevier Applied Science, London, Chapter 6). However, opposite findings are also documented. Wong et al. (1995) revealed that vitamin E is more effective than rosemary extract in a cooked beef homogenate. Additionally, rosemary extract is shown to be a synergist of vitamin E in stabilizing or retarding oxidation in sardine oil and fish muscle (Fang, X. and S. Wanda (1993), “Enhancing the antioxidant effect of α-tocopherol with rosemary extract in inhibiting catalyzed oxidation caused by Fe2− and hemoprotein”, Food Res Int 26: 405-411; Wanda, S. and X. Fang (1992), “The synergistic antioxidant effect of rosemary extract and α-tocopherol in sardine oil model system and frozen-crushed fish meat”, J Food Process Preserv 16: 263-274).
As to the extraction of rosemary, many authors report that polar solvents yield extracts with higher antioxidant activities (Chang, S. S., B. Ostric-Matijasevic, C-L Huang and OA-L Hsieh (1977), “Natural antioxidants from rosemary and sage”, J Food Sci 42: 1102-1106). Chen et al. (1992) found that hexane extracts of rosemary contained a higher content of carnosic acid and carnosol than methanol extracts do. Carnosic acid and carnosol are the effective antioxidant molecules in rosemary. Carnosic acid and carnosol have been suggested to account for over 90% of the antioxidant activity of rosemary extracts (Aruoma, O. I, B. Halliwell, R. Aeschbach and J. Loligers (1992) “Antioxidant and pro-oxidant properties of active rosemary constituents: carnosol and carnosic acid”, Xenobiotica 22: 257-268). Antioxidant molecules in general, and rosemary antioxidants specifically, are by nature labile molecules especially when exposed to heat and/or air. During the harvest, the drying, and the regular solvent extraction of rosemary, some oxidation is likely to occur. Through a process of chemical reactions, carnosic acid, the naturally-occurring antioxidant molecule in rosemary, is believed to be the precursor to carnosol and many other antioxidants found therein (Wenkert, E., A. Fuchs, J. D. McChesney (1965), “Chemical artifacts from the family labiate”, J. Org. Chem. 30: 2931-2934). It can be demonstrated that the freshly cut leaves of rosemary do not contain carnosol (Aeschbach, R. and L. Philippossian (1993), “Carnosic acid obtention and uses”, U.S. Pat. No. 5,256,700). Carnosic acid is about 10 times more effective as an antioxidant than carnosol (Aruoma et al., 1992), and it, therefore, is important for the high activity of a rosemary extract to minimize the damage to carnosic acid.
Essential oils are volatile oils which are the aroma and flavor components of organic material. They are used in a variety of products such as incense, aromatherapy oils, perfumes, cosmetics, pharmaceuticals, beverages, and foods. The market for these oils demands consistent high quality and reliable supplies at competitive prices. Essential oils are typically commercially extracted from organic material such as rosemary using steam distillation. In this prior art process, the antioxidants are destroyed, and thermal degeneration of the essential oils may occur.
The antioxidant activity of commercially available rosemary products was compared with rosemary extracts prepared in the laboratory using various solvents for extraction. It was found that the antioxidant activity of commercial rosemary products was in the range of 2-5% when compared to mixed tocopherols. A methanol extract had 10% of the activity of mixed tocopherols. Methanol extraction, moreover, results in a dry powder that is difficult to dissolve into preferred carriers, such as edible oils. Accordingly, there were identified goals to increase the specific activity of extracts of species of the family Labiatae, including rosemary, by optimizing the solvent extraction methodology, to test alternate extraction technologies, and to improve the handling characteristics of the extract.
The investigation into alternate extraction technology had two primary objectives. Firstly, to increase the specific activity of the rosemary extracts further for more efficient formulation into soybean oil or other carrier; and, secondly, to identify technology allowing the removal of the essential oil fraction from the extracted material without oxidative destruction of the carnosic acid. One extraction technique investigated is based on tetrafluoroethane (TFE).
A process for the extraction of antioxidants and essential oils from rosemary preferably meets several criteria. It should be economical and also lead to a liquid or oil antioxidant extract that can be formulated into a homogeneous, soybean oil-based final product that is largely free of odor.
For the foregoing reasons, it is desired that a process be found that simultaneously yields antioxidants and essential oils suitable for further commercial use via a single solvent mix. The present invention solves this problem with sufficiently high yields and purities to be a commercially-viable process.